Method of and means in heating of subsurface fuel-containing deposits &#34;in situ&#34;



Sept. 1 1959 Filed Sept. 1. 1953 G. J. w. SALOMONSSON ETAL METHOD OF AND MEANS. INHEATING OF SUB-SURFACE FUEL-CONTAINING DEPOSITS "IN SITU" 2 Sheets-Sheet 1 s. we 7 17 a s L iIK- Ma 4 AT'TORNYEY Sept. 1, 1959 G.-J. w. sALoMoNssoN ET AL 2,

METHOD OF AND MEANS IN HEATING 0F SUB-SURFACE FUELCONTAINING DEPOSITS "IN SITU" Filed Sept. 1. 1953 2 Sheets-Sheet 2 ..III. 1 1:11:11 fhrnnnllinllrllvlnii r/"is INVENTORS I cbs'rA; -J.W. SALOMONSSON BENGT PERSSON ATTORNEY United States Patent METHOD OF AND MEANS IN HEATING OF SUB- SURFACE FUEL-CONTAINING DEPOSITS 1N SITU Giista Johan Wilhelm Salomonsson, Hallabrottet, and Bengt Persson, Knmla, Sweden, assignors, by direct and mesne assignments, of one-half to Svenska Skifferolje Aktiebolaget, Orebro, Sweden, a Swedish jointstock company, and one-half to Husky Oil Company, Cody, Wyo., a corporation of Delaware Application September 1, 1953, Serial No. 377,952

Claims priority, application Sweden July 17, 1953 16 Claims. (Cl. 262-3) This invention relates to a method and means in the exploitation of geological deposits for the recovery of fluid or/ and gaseous products by heating of said deposits in situ, i.e. in place in the earth.

More particularly this invention relates to a method and means in the exploitation of sub-surface fuel-carrying deposits for the recovery of valuable fluid or/ and gaseous products by direct heating of said deposits in situ, i.e. in their natural location. Deposits adapted to be exploited in this manner are, for example, shale formations, tar-sand and sulphur deposits.

The heating in situ is performed to a large extent, at least as far as it is applied to shale formations, by means of electric heating members driven down and introduced into the formation to be exploited.

In the exploitation of fuel-carrying deposits by heating in situ considerable quantities of combustible gas are obtained. One object of the present invention is to provide a method and means permitting directly to use said gas as fuel in the heating operation. In this way it is possible to avoid part of the losses and additional costs inherent to the circuitous way over a steam-operated power plant using the recovered gas as fuel for boilers.

When using a convenient gas burner in a long tubular heating member which for various reasons has proved to be the most suitable equipment for the direct heating of sub-surface deposits, there will be caused a very ununiform distribution of temperature over the heating member with a distinct top of the heating curve around the flame proper. In order to avoid this drawback it has been proposed to dispose a plurality of flames on various levels within the long tubular heating member. The realization of this proposal is, however, greatly obstructed by difficulties in obtaining for each of the individual flames the most suitable proportion between the quantities of supplied fuel and oxygen.

A further object of the invention is to provide a method ensuring uniform distribution of temperature along the tubular heating member in spite of the presence of one flame only.

Still a further object of the invention is to provide various means adapted to influence the distribution of temperature along the tubular heating member and in particular in the vicinity of the single flame.

Further objects and advantages will be apparent from the following description considered in connection with the accompanying drawings which form part of this specification and of which:

Fig. 1 is a longitudinal section through a heating member embodying the invention.

Fig. 2 is a section on line IIII of Fig. 1.

Fig. 3 is a longitudinal section through a modified heating member embodying the invention.

Fig. 4 is a longitudinal section through a further modi- "ice ' tubes denoted by 10, 12 and 14, respectively. The innermost tube 10 is by means of a stufling box 11 connected to one end of the intermediate tube 12, said intermediate tube in turn by means of a stufling box 13 being connected to one end of the outermost tube 14. Said external tube 14 is at its end remote from the stuffing box 13 provided with a bottom 15. Spaced apart from said bottom 15 is the free end of the intermediate tube 12 located inside the external tube 14. The corresponding free end of the internal tube 10 is under operation located substantially further spaced from the bottom 15 than is the free end of the intermediate tube 12. The internal tube 10 is, however of equal length as the other tubes, due to which fact the major part of said tube 10 normally projects outside the external and intermediate tubes 14 and 12, respectively, which implies that it is on the opposite side of the stuffing box 11 seen from the bottom 15. This arrangement renders possible on certain occasions, for instance when igniting the member, to displace the internal tube 10 within the stufling box 11 so as to approach its mouth to the bottom 15. The intermediate tube 12 is also displaceable within the stufling box 13 relative the external tube 14. At its end remote from the bottom 15 the external tube 10 is sealed by means of a lock 16 and adjacent thereto provided with a connecting tube 17. Similar connecting tubes 18 and 19, respectively, are attached to the intermediate tube 12 and the exterior tube 14 adjacent the corresponding stutfing boxes 11 and 13, respectively. In order to obtain requisite guidance of the three concentric tubes 10, 12 and 14 relative to one another, short pieces 20 of rod iron are inserted in the interspaces between said tubes. As will be seen from Fig. 2, these pieces 20 of rod iron are displaced relative to one another by and secured by welding to the interior face of those two tubes which form the interspace.

The fuel to be burned is supplied through the connecting tube 17 into the internal tube 10, the required air of combustion being allowed to enter the interspace between the internal tube 10 and the intermediate tube 12. Upon ignition a flame will develop at the free end of the internal tube 10. The hot flue gases formed will flow in the intermediate tube 12 in the direction towards the bottom 15. On their arrival there they are forced to turn and are then allowed in the opposite direction to enter the interspace between the external tube 14- and the intermediate tube 12 and to escape through the connecting tube 19. During their path from the flame to the bottom 15 and back to the outer interspace the flue gases transmit part of their heat content to the surrounding tube walls. As far as the intermediate tube 12 is concerned the temperature transmitted is highest around the flame and decreases uniformly along the longitudinal extension of the tube towards the bottom 15. Upon the turn and further flow in the opposite direction of the flue gases their temperature continues to fall. The heat delivered thereunder from the flue gases to the wall of the external tube 14 will thus be greatest adjacent the bottom 15 and then decrease in the direction towards the connecting tube 19. This effect is totally or at least partly counteracted by the external tube 14 also receiving an additional supply of heat from the intermediate tube 12 by radiation from this latter. As the temperature of the intermediate tube 12 is the high est and consequently the heat radiation therefrom has its aximum round t fl m n de e e a d bottom 15, the result will be that the total quantity of heat transmitted within a pre-determined unit of time y q h-ra qn and qnve iqn qm the me be 14 will be approximately the same for each length unit at he e e nal tube 14. be w n its b o n s PO tion located sti'aight opposite the flame. As far as that part of the external tube is concerned, which is located bfilWeen the flame and the connecting tube 19, the heat supply to the tube wall is considerably lower, since any additional heat from the intermediate tube is not received. On the contrary, the entering combustion air has some cooling eflect on the escaping flue gases. In this way part of the heat inherent to the escaping flue gases will be utilized in pro-heating the combustion air.

With the construction described above a relatively uniform distribution of temperature is obtained for that part of the external tube 14, which is located between the free opening of the internal tube 10 and the bottom 15. A somewhat higher temperature is, however, prevailing nearest to the flame. Equalization of this difference in temperature may be brought about by providing the intermediate tube 12 to a suitable extent with an encasing protection 21 to radiation as is shown in Fig. 3. Another expedient is to cover either the intermediate or the external tube to a desired extent with an insulating layer 24.

Another possibility of exerting an equalizing effect on the distribution of temperature along the external tube consists in varying the velocity of flow of the flue gases and thereby also the delivery of heat from them by varying the area of passage open to said gases. Byincreasing the velocity of the flue gases the k-value will be improved, but due to the shortened time of stay the delivery of heat will nevertheless be reduced. A means for providing variations of the area of passage is presented in Fig. 4 showing the intermediate tube 12 provided with an external bulbous tube piece 22, which may be displaceable on the tube 12.

Big. finally shows a device for igniting the heating member constructed according to the invention. This ignition is performed by inserting an ignited rocket 23 into the internal tube 10, which then must be placed so as to have its mouth immediately above the bottom 15. In this way condensate is prevented from collecting in the external tube on said bottom. Such condensation would occur easily unless the parts adjacent the bottom are heated sufliciently quickly. i

The gaseous fuel may entirely or partly be replaced by liquid or finally divided solid fuel. The combustion air may entirely or partly be replaced by oxygen or an oxygen-containing gaseous mixture. V While several more or less specific embodiments of the invention have been shown, it is to be understood that this is for purpose of illustration only and that the invention is not to be limited thereby, but its scope to' be determined by the appended claims.

What we claim is:

1. A method of heating which comprises maintaining flame-developed combustion at a central combustion zone, conducting the hot flue gases in a flow passage leading away from said combustion zone, reversing the flow of said flue gases, and conducting said reversed flow of flue gases in a zone surrounding said flow passage and said combustion zone in counter current to the direction of flow of the flue gases from said combustion zone, the flow passage and the zone surrounding said flow passage being mechanically separate but in heat conducting relation with each other, and the zone surrounding said flow passage being sealed against exit of gases therefrom to material undergoing heating, thereby combining the effects of radiation and convection from both the flame and the flue gases to give an elongatedheating zone of substantially uniform temperature. V V

2. The method of claim 1 in which the cross-sectional area for the flow passage of the escaping flue gases is varied to modify the distribution of temperature in said elongated zone.

3. The method of claim 1 in which the effect of radiation is modified by restricting radiation from any more highly heated zone.

4. The method of claim 3 in which the modification of the effect of radiation is performed around the flame t the com us i Z 5. The method of claim 3 in which the modification of the effect of radiation is performed along at least part of the path of the flue gases.

6. The method of claim 3 in which the effect of heat transmission is modified by heat insulation.

7. The method of claim 6 in which the modification of the effect of radiation is performed around the flame at the combustion zone.

8. The method of claim 6 in which the modification of the effect of radiation is performed along at least part of the path of the flue gases.

9. The method of claim 1 in which the combustion is supported by fuel supplied to the combustion zone.

10. The method of claim 1 in which sub-surface fuelcontaining deposits are heated in situ for recovery of valuable products therefrom.

11. The method of claim 10 in which gas is supplied to the. composition zone from gas formed by heating the sub-surface deposit.

12. A method of heating sub-surface deposits in situ for recovery of valuable products in fluid condition by introducing into the deposit, tubular members disposed substantially concentrically one within another, of which members, the outermost is sealed at its lower end, one tubular member enclosed by and adjacent to said outer most tubular member having an outlet located above said sealed end in which a flame-developing combustion of a mixture containing fuel and a combustion-sustaining medium is effected, in a combustion zone, characterized in that the flue gases from the combustion zone formed within the innermost tubular member in spaced relationship to the upper end thereof are caused to flow in a downward direction and thereafter back in opposite direction inside the annular space between two outer tubular members and in heat conductive connection with the downwardly directed flow of flue gases from the innermost tubular member whereby the combined effect of convection and radiation from the flue gases and said flame produces a desired equal distribution of the heat and thereby substantially uniform temperature of the outermost tubular member in the longitudinal direction thereof.

13. A method according to claim 12, characterizedin that a portion of the gas involved by heating of the de: posit is returned to the combustion zone and used there as fuel.

14. A heatingdevice for heating sub-surface deposits, characterized by three substantially concentric tubes of which the outermost is sealed at is base, the intermediate tube opening into the first-mentioned tube in spaced relationship above the sealed base of said first-mentioned tube, the innermost tube opening into the intermediate tube at a still higher level above said sealed base, said two inner tubes being connected with an inlet each for supply of fuel and combustion sustaining medium, respectively, and theannular space between said intermediate and said first-mentioned tube having an escape opening for the fuel gases produced in the combustion zone located within the intermediate tube below the opening of the innermosttube.

15. A device according toclaim 14 wherein the several tubes are axially displaceable relatively to one another.

16. A device according to claim 14 wherein are proi 1 1- Pr ect o ev ce aga ns ra iation, and, insulating 5 layers disposed around the flame and path of the flue 2,497,868 gases and around the combustion zone. 2,506,853 2,732,195 References Cited in the file of this patent UNITED STATES PATENTS 5 1,170,266 Huff Feb. 1, 1916 155,732 1,449,420 Kreager et a1 Mar. 27, 1923 537,657 1,724,783 Smallwood et a1 Aug. 13, 1929 123,137

6 Dalin Feb. 21, 1950 Berge et a1. May 9, 1950 Ljlmgstrom Jan. 24, 1956 FOREIGN PATENTS Great Britain Dec. 30, 1920 Great Britain July 1, 1941 Sweden Nov. 9, 1948 

1. A METHOD OF HEATING WHICH COMPRISES MAINTAINING FLAME-DEVELOPED COMBUSTION AT A CENTRAL COMBUSTION ZONE, CONDUCTING THE HOT FLUE GASES IN A FLOW PASSAGE LEADING AWAY FORM SAID COMBUSTION ZONE, REVERSING THE FLOW OF SAID FLUE GASES, AND CONDUCTING SAID REVERSED FLOW OF FLUE GASES IN A ZONE SURROUNDING SAID FLOW PASSAGE AND SAID COMBUSTION ZONE SURROUNDING CURRENT OT THE DIRECTION OF FLOW OF THE FLUE GASES FROM SAID COMBUSTION ZONE, THE FLOW PASSAGE AND THE ZONE SURROUNDING SAID FLOW PASSAGE BEING MECHANICALLY SEPARATE BUT IN HEAT CONDUCTING RELATION WITH EACH OTHER, AND THE ZONE SURROUNDING SAID FLOW PASSAGE BEING SEALED AGAINST EXIT OF GASES THEREFROM TO MATERIAL UNDERGOING HEATING, THEREBY COMBINING THE IFFECTS OF RADIATION AND CONVECTION FROM BOTH THE FLAME AND THE FLUE GASES TO GIVE AN ELONGATED HEATING ZONE OF SUBSTANTIALLY UNIFORM TEMPERATURE. 